GB2050163A - Anti-perspirant sticks - Google Patents

Description

1 GB2050163A 1

SPECIFICATION

Anti-perspirant composition This invention relates to an anti-perspirant composition and, more particularly, to an anti- 5 perspirant composition suitable for use in stick-form and of the so- called dry-feeling type comprising an emulsion of an aqueous solution of an astringent in a solid matrix comprising a volatile, water-insoluble liquid and having stability relative to separation in the molten state and stability relative to leaking in the solid state.

Anti-perspirant composition are well known in the cosmetic art. These compositions are 10 formulated as aerosols, gels, sticks, creams, pump sprays and lotions and comprise an astringent, typically comprising one or more zirconium salts and/or aluminium salts, in various forms such as a dry, impalpable powder, an alcohol solution or an aqueous solution. Of these various forms of astringents the aqueous solution is known to be the most effective anti- perspirant.

However, an anti-perspirant composition having water as the continuous phase, such as an aqueous solution of an astringent, or an oil-in-water type emulsion thereof, is less desirable than a composition comprising a dry powder or an alcohol solution thereof because it has a wet feel when applied to the human skin and goes through a tacky state during the drying period after application.

U.S. Patent No. 4,122,029 disclosed water-in-oil type compositions having broad utility and comprising a polydiorganosiloxane-polyoxyalkylene copolymer and a water-in-oil type surfactant. When formulated as an antiperspirant emulsion of an aqueous solution of an astringent, such as aluminium chlorhydrate, emulsified in a volatile, non-aqueous continuous phase these composi- tions have a desirable dry feeling when applied to the human skin and do not exhibit the wet- 25 and-tacky effect described above.

U.S. Patent Application Serial No. 46,590, filed June 7, 1979 disclosed new anti-perspirant compositions which have improved efficacy compared to the anti- perspirants of U.S. Patent No.

4,122,029 and do not exhibit the wet-and-tacky effect.

Although water-in-dil type anti-perspirant compositions such as those of U.S. Patent No. 30 4,122,029 and of U.S. Patent Appin No. 46,590 may be formulated in several forms, such as lotions, gels and sprays using well-known methods, the preparation of stick-forming composi tions therefrom which do not separate in the molten state and which solidify to a non-leaking stick has not been entirely successful using the conventional teaching of the art.

Cosmetic sticks, such as anti-perspirant sticks, are typically prepared by first preparing a molten, solidifiable composition comprising all components and thereafter casting the molten composition in- the desired shape and/or dispenser. When the molten composition is an emulsion successful completion of this process requires that the emulsion be stable against separation. In addition, the resulting stick must not leak, i.e. lose liquid. The usual mixing of singular gelling agents with the compositions of U.S. Patent No. 4,122, 029 and of U.S. Patent 40 Appl. No. 46590 do not satisfy these requirements.

We have therefore sought to provide anti-perspirant compositions of the water-in-oil type suitable for use in stick-form without leaking. We have further sought to provide anti-perspirant emulsion compositions of the water-in-oil type which are stable in the molten state.

Thus, according to the present invention an anti-perspirant composition is provided by mixing 45 a stick-forming mixture of components consisting essentially of a solid alkonoic acid, such as stearic acid, and a waxy ester, such as spermaceti wax, optionally containing up to three parts by weight of a solid alkanol, such as stearyl alcohol, for every one part of waxy ester, with water-in-oil type anti-perspirant emulsion components comprising a polydiorganosiloxane-polyox yalkylene copolymer. The solid alkanoic acid is used in sparing amounts to control crystallinity 50 in, and thus prevent leaking of, the anti-perspirant stick while the waxy ester is used in sufficient amounts to confer stability to the molten composition.

It is postulated that the composition according to this invention is successful because the solid alkanoic acid and waxy ester, in addition to providing the solidifying action for stick formation, also serve additional function. This, it is believed that the solid alkanoic acid serves as an auxiliary water-in-oil type surfacant while the waxy ester has better compatibility with the primary water-in-oil type surfactant, i.e. the polydiorganosiloxane- polyoxyalkylene copolymer, and the volatile liquid than do the solid alkanols usually used in stick formulations.

Thus the present invention provides an anti-perspirant composition comprising (a) 30 to 60 parts by weight of an aqueous solution of an astringent as a discontinuous phase dispersed in a 60 solid matrix Comprising (b) 18 to 30 parts by weight of a volatile liquid having a normal boiling point of less than 250C comprising a methylsiloxane fluid having the average unit formula 0 35.

GB2050163A 2 (CH3)aSio4-a/2 wherein a has an average value of from 2 to 3, inclusive, or a paraffinic hydrocarbon fluid (c) 1 to 5 parts by weight of at least one solid alkanoic acids having at. least 12 carbon atoms pr molecule, (d) 1 to 5 parts by weight of a polydiorganosiloxane-polyoxyalkylene copolymer containing at least one polydiorganosiloxane segment comprising siloxane units of the formula IRSiO,-b/2 wherein b has a value of from 0 to 3, inclusive, there being an average value of approximately 2 R radicals per silicon for all siloxane units in the copolymer, and R denotes a methyl, ethyl, vinyl or phenyl radical of a divalent radical bonding a polyoxyalkylene segment to the polydiorganosiloxane segment, at least 95 percent of all R radicals being methyl; and at least one polyoxyalkylene segment having an average molecular weight of at least 1000 and consisting of from 0 to 50 mol percent polyoxypropylene units and from 50 to 100 mol percent polyoxyethylene units, at least one terminal portion of the polyoxyalkylene segment being bonded to the polydiorganosiloxane segment, any terminal portion of the polyoxyalkylene segment not bonded to the polydiorganosiloxane segment being satisfied by a terminating radical; the weight ra tio of polydiorganosiloxane segments to polyoxyalkylene segments in the copolymer having a value of from 2 to 8 and (e) 20 to 30 parts by weight of at least one waxy ester or a mixture of one part by weight of at least one waxy ester with up to 3 parts by weight of at least one solid alkanol having at least 12 carbon atoms per molecule, the sum total of components (a), (b), (c), (d) and (e) being 100 parts by weight.

Component (a) is an aqueous solution of any astringent anti-perspirant agent. Examples of well-known astringents include the aluminium, hafnium and zirconium salts, such as zirconyl hydroxide halides, zircon iu m-alu miniu m complex saltsi aluminium chloride, sodium aluminum lactate, basic aluminium halides such as A12(01-1),Cl, aluminium bromide and the water, alcohol or glycine complexes.thereof.

The amount of astringent that is dissolved in water to form component (a) may vary widely 30 and is not critical; however, certain practical limitations exist. On the one hand an efficacious anti-perspirant composition should contain sufficient astringent to provide perspiration reduction, although compositions containing less astringent are useful as personal care compositions.

Preferably the anti-perspirant composition comprises approximately 15 to 30 weight percent astringent. On the other hand it is desirable to maximize the amount of water in the anti- 35 perspirant formulation without negating utility, for obvious economic reasons. Depending on the particular astringent that is used, component (a) may vary in concentration from as little as one part by weight astringent per three parts by weight water up to a saturated aqueous solution of the astringent. Considering economy and efficacy, a particularly useful component (a) is an aqueous solution of aluminium chlorhydrate consisting of equal weight portions of water and 40 aluminium chlorhydrate.

The volatile liquid (b) is a methylsiloxane fluid a paraffinic hydrocarbon fluid or a mixture of these two fluids, further detailed below. To be suitable as a volatile fluid for an anti-perspirant composition component (b) should have a boiling point of less than 25WC. at atmospheric pressure. Methylsiloxane fluids and paraffinic hydrocarbon fluids meeting this parameter also typically have a viscosity at 2WC of less than 10 millipascal-seconds (mPa.s). One millipascal second equals one centipoise. To avoid an excessive cooling effect for the user of the composition according to this invention it is preferred that at least a portion of the volatile liquid has a normal boiling point of from 1 OWC to 20WC.

The volatile methylsiloxane fluid (b) has the average unit formula (CH3)asiO4-a/2 wherein a has an average value of from 2 to 3 and consists of siloxane units of formula (CH3)3S'01/2' (CH3)2S'02/2, CH3S'O3/2 and S'04/2 units.

Preferably the volatile methylsiloxane fluid consists essentially of dimethylsiloxane units and optionally trimethylsiloxane units. Of particular value as volatile liquid (b) are the cyclic siloxanes of the general formula [(CH,)2SiO], and the linear siloxanes of the general formula (CH3)3SiO[(CH3)2S'O]ySi(CH3)3, and their mixtures, wherein x is an integer of from 3 to 6 and y is 0 or an integer of from 1 to 4. A highly preferred methylsiloxane fluid is a mixture of the cyclic 0 siloxanes wherein a major portion is the tetramer (x= 4).

Paraffinic hydrocarbon fluids suitable for use as component (b) in these compositions correspond to the average formula C,,H2n + 21 wherein n is an integer having a value of less than 15. A particularly suitable paraffinic hydrocarbon fluid is a high-purity isoparaffin available from W 1.

f 3 GB2050163A 3 Exxon Corporation as Isopar (Trade Mark).

The volatile fluid, in addition to being a methylsiloxane fluid or a paraffinic hydrocarbon fluid, may be any mixture of the methylsiloxane fluid and the paraffinic fluid, such as a mixture of octamethylcyclotetrasiloxane and hexane or decamethylcyclopentasiloxane and hexane or a 5 mixture of two or more of the cyclosiloxanes and one or more paraffins.

Methylsiloxane fluids and paraffinic hydrocarbons, suitable for use as the volatile fluid (b) in the compositions of this invention, are well known in the chemical and polymer arts; many are commercially available.

Component (c) is a stick-stabilizing component comprising a solid alkanoic acid having at least 12 carbon atoms per molecule. By solid it is meant that the alkanoic acid has a melting point 10 above 20'C and preferably above 40'C.

Component (c) is preferably a solid alkanoic acid the type which is widely used in the cosmetic art, such as palmitic acid and stearic acid. Component (c) may be a single alkanoic acid or a mixture of two or more alkanoic acids an may be of synthetic and/or natural origin.

It should be noted that although many alkanoic acids having 12 or more carbon atoms can be 15 prepared in essentially pure form, they are usually used in the cosmetic art as mixtures. For example, stearic acid is predominantly CH,(CH2)1,COOH; but, depending on its method of preparation, it has mixed therewith varying amounts of palmitic acid. Trace amounts of other byproduced components such as ethylenically unsaturated acids, fats and oils may also be present.

For the purposes of this invention component (c) preferably comprises more than 95 percent by 20 weight, and most preferably more than 99 percent by weight, solid alkanoic acid having an average of at least 12 carbon atoms per molecule.

Component (c) is referred to as a stick-stabilizing component because its omission from the compositions of this invention results in a crystalline anti-perspirant stick that "leaks", i.e. oozes fluid.

Component (d) is a polydiorganosiloxanepolyoxyalkylene copolymer containing at least one polydiorganosiloxane segment and at least one polyoxyalkylene segment. The polyoxyalkylene segments may be bonded to the polydiorganosiloxane segments with silicon-oxygen-carbon bonds and/or with silicon-carbon bonds. Although component (d) is insoluble in water and is therefore not subjected to vigorous hydrolysis in the compositions of this invention, it is preferred that the copolymer (d) has silicon-carbon bonding instead of the more hydrolyzable silicon-oxygen-carbon bonding joining the-polyoxyalkylene segments to the polydiorganosiloxane segments.

The polydiorganosiloxane segments of the copolymer (d) comprise siloxane units which are interlinked by Si-O-Si linkages and which have the formula IR,SiO,_b/, 1 W The value of b may range from 0 to 3 for said siloxane units with the provision that there is an average of approxirnkely 2, i.e. from 1.9 to 2.1 R radicals for every silicon atom in the 40 copolymer. Suitable siloxane units thus include R3SiO,,2, R2Si0212, IRS'O, /2, and Si04/2 sifoxane units taken in molar amounts such that b has an average value of approximately 2 in the copolymer. The siloxane unit may be arranged in linear, cyclic and/or branched fashion.

The R radicals of copolymer (d) may be a methyl, ethyl, vinyl, or phenyl radical or a divalent radical bonding a polyoxyalkylene segment to the polydiorganosiloxane segment. At least 95 45 percent of all R radicals in the copolymer (d) must be methyl radicals; and preferably there is at least one methyl radical bonded to each silicon atom in component (d). Divalent R radicals preferably contain no more than 6 carbon atoms. Examples of suitable divalent R radicals include 0-0, -CH2mO-, -C,H2,,,and -CH2n7C02- where m is an integer greater than zero.

Illustrative of the siloxane units that make up the polydiorganosiloxane segments of the - 50 copolymer (d) are the following, where Me denotes methyl and Q denotes said divalent R radical and bonded polyoxyalkylene segment: R3Si01/2 units such as Me3Si01/2, Me2(CH2 = CH) Si01/2, Me2(C61-1,)SiO,,2, Me(C^)(C1-12 = CH)Si01/2, Me2(CH,Cl-12) i01,2, MeASA/2, Mea2S'01/2, C13S'01,2, QAH3CH2P01,2, and Me(C,HJ(Q)S'0112; R2S'02/2 units such as Me2SiO2/2, Me(C6H,) Si02,2, Me(CH2 = CH)Si02/2, (C,H5)2SiO2/2, MeQS'02,2, and Q(C^)Si02/2; RS'03/2 units such as 55 MeSi03,2, C.H.Si03,2, CH2 = CHS'03/2, CH3CH2SA/2 and QSi03,2; and Si04/2 units.

It is to be understood that copolymer (d) may comprise one or more of the polydiorganosilox ane segments. The number of an average molecular weight of the polydiorganosiloxane segments in the copolymer is related to the desired weight ratio, hereinafter described, of the segments in the copolymer. Preferably copolymer (d) comprises one polydiorganosiloxane 60 segment having bonded thereto one or more polyoxyalkylene segments.

The polyoxyalkylene segments of the copolymer (d) comprise oxyethylene units of the formula -CH2CH20-, alone, or in combination with oxypropylene units of the formula -CH2CH(CH3)0-, an average of at least half of the oxyalkylene units in the polyoxyalkylene segments being oxyethylene units. Suitable emulsions of this invention are not formed when the polyoxyalkylene 65 4 GB2050163A 4 segments contain more than 50 mol percent of the relatively hydrophobic oxypropylene unit.

The polyoxyalkylene segments thus correspond to the formula E-CH2CH20-1 P[-CH,CH (CH3)0-]q wherein the oxyalkylene units may be arranged in any suitable fashion such as random, alternating and block. The average values of p and q are such that pi__-q and the sum of p+ q is sufficient to provide an average molecular weight of at least 1, 000 for the polyoxyalky- 5 lene segments. Preferably the average molecular weight of the polyoxyalkylene segments has a value of from 1,500 to 5,000.

The polyoxyalkylene segments of the copolymer (d) are bonded to the polydiorganosiloxane segments of the copolymer by at least one terminal portion of the polyoxyalkylene segment, the bonding being by way of a divalent R radical, hereinbefore described. It is to be understood that 10 the bonding may be by both terminal portions of the polyoxyalkylene segment in those copolymers comprising more than one polydiorganosiloxane segments. Any terminal portion of the polyoxyalkylene segment of copolymer (d) that is not bonded to a polydiorganosiloxane segment is satisfied by a terminating radical. The type of terminating radical is not critical and it be-monovalent, thereby terminating one polyoxyalkylene segment, or polyvalent, thereby terminating more than one polyoxyalkylene segment. The terminating radicals are made up of atoms comprising carbon, hydrogen, nitrogen and oxygen. Illustrative of suitable terminating radical are hydrogen; hydroxyl; alkyl, such as methyl, ethyl, propyl, butyl; benzyl; aryl, such as phenyl; alkoxy such as methoxy, ethoxy, propoxy, butoxy; benzyloxy; aryloxy, such as phenoxy; alkenyloxy, such as vinyloxy and allyloxy; acyloxy, such as acetoxy, acryloxy and propionoxy and 20 amino such as dimethylamino.

The number of and average molecular weights of the segments in the copolymer (d) are such that the weight ratio of polydiorganosiloxane segments to polyoxyalkylene segments in copolymer (d) has a value in the range from 2/1 to 8/1, and preferably from 2.5/1 to 4.0/1. This weight ratio will insure that the copolymer (d) has a preferantial solubility in the volatile liquid, a 25 condition necessary for the formation of stable water-in-oil type emulsions of this invention.

The weight ratio of polydiorganosiloxane segments to polyoxyalkylene segments in copolymer (d) is calculated on the basis of the total weight of polydiorganosiloxane and the total weight of polyoxyalkylene that is joined in the copolymerization process. For example, if 100 parts by weight of polydiorgariosiloxane is joined completely by an addition process, which utilizes silicon-bonded hydrogen radicals, with 20 parts by weight of polyoxyalkylene, the weight ratio of the resulting copolymer has a value of 5. Of course, if the complete joining is accomplished by a displacement reaction, involving a silicon-bonded hydrolyzable radical and resulting in the formation of a by-product, the weight ratio of polydiorganosiloxane to polyoxyalkylene in the resulting copolymer may not be identical with the weight ratio of the corresponding reactants, due to the loss of the weight of the displaced groups. The error intrduced into the calculation of the weight ratio by ignoring the loss of the displaced groups is usually insignificant. That is to say, the weight ratio of polydiorganosiloxane to polyoxyalkylene in copolymer (d) may be calculated from the weight of reactants that react to form the copolymer or the weight ratio may be determined by suitable analysis of the resulting copolymer itself. Since analytical techniques 40 such as elemental analysis, nuclear magnetic resonance spectroscopy, silicon substituent analysis and infra-red spectroscopy may be found in "Analysis of Silicones", A. Lee Smith, Ed., John Wiley and Sons, New York, 1974.

As used herein, the term "copolymer" means either a block arrangement of segments such as denoted by the formulae (AB), A(BA), and B(AB), or a pendant arrangement of segments such 45 as (ABd), or combinations thereof wherein A denotes a polydiorganosiloxane segment, B denotes a polyoxyalkylene segment and c and d denote integers greater than zero and greater than one, respectively.

Copolymers (d) may be prepared by modification of the well-known methods described in the polydiorganosiloxane-polyoxyalkylene copolymer art such as United States Patents No.

2,868,824; Re 25,727; No. 3,172,899; No. 3,234,252; No. 3,174,987; No. 3, 562,786; No.3,600,418; No. 3,629,308; No. 3,629,165; and No. 4,122,029.

It is to be understood that the silicon-bonded reaction groups such as silicon-bonded hydrogen for addition reactions or silicon-bonded hydrolyzable radicals for displacement reactions are preferably completely reacted in the copolymer preparation process, but that trace amounts of said reaction groups may escape reaction with the polyoxyalkylene and may be found in the copolymer (d).

Component (e) is an emulsion-stabilizing component comprising a waxy ester or a mixture thereof with a limited amount of a solid alkanol having at least 12 carbon atoms per molecule.

Component (e) is referred to as an emulsion-stabilizing component because its omission from 60 the composition of this invention or its dilution with more than three parts of solid alkanol per one part of waxy ester results in a molten composition which demonstrates very little resistance to separation in the molten state.

The term waxy ester means compounds of the formula C,,H2,,,,CO,CPH2,11 wherein e and f have values so that the ester is a solid below 20'C, and preferably below 40C. Preferably the 65 s GB2050163A 5 waxy ester is a waxy ester of the type widely used in the cosmetic art, such as spermaceti wax, cetyl palmitate, stearyl palmitate, beeswax and myricyl palmitate. The waxy ester may be a single waxy ester or a mixture of two or more of such waxy esters and may be of synthetic and/or natural origin.

It should be noted that although many waxy esters can be prepared in essentially pure form, they are usually used in the cosmetic art as mixtures. For example, natural spermaceti wax is predominantly cetyl palmitate; however it contains small amounts of cetyl alcohol; esters of lauric, stearic and myristic acid and esters of higher alcohols. Trace amounts of other esters may also be present, such as esters of long chain olifinically unsaturated acids, dicarboxylic acids and hydroxyl acids.

The hardness of the stick compositions of this invention, which affects the glide, i.e. ease of application, and payout, i.e. rate of application, of the stick, is directly related to, among other parameters, the melting point of the waxy ester.. For a desirable payout and glide the waxy ester preferably has a melting point between 2WC and WC; however, higher melting waxy esters may be mixed therewith in small amounts, particularly when the hardness of the stick is further 15 controlled by varying other parameters which directly affect harness, such as the amount and melting point of any alkanol that may be mixed with the waxy ester and the total amount of component (e) that is present in the composition.

Component (e) may consist solely of a waxy ester or the waxy ester may be mixed with up to t three parts by weight, for every part by weight of the waxy ester, of a solid alkanol having at 20 least 12 carbon atoms per molecule. Stability of the molten composition, hereinabove discussed, is not obtained when this weight ratio of solid alkanol to waxy ester is appreciably larger than 3.

Any solid alkanol that is present in the waxy ester, such as impurity amounts of cetyl alcohol, contributes to the value of this ratio.

By solid it is meant that the alkanol has a melting point above 2WC, but, preferably, not 25 above WC. Preferably any alkanol that is used is one of the group of alkanols which are widely used in the cosmetic art such as lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol.

The compositions of this invention comprise 30 to 60 parts by weight of the aqueous solution of an astringent (a), dispersed in 40 to 70 parts by weight of a solid matrix comprising (b) to (e), 30 the total of the aqueous solution and the solid matrix being 100 parts by weight. In a preferred embodiment the aqueous solution of astringent consists of a 50/50 weight mixture of water and aluminium chforhydrate and accounts for 40 to 50 parts by weight of the 100 parts by weight of the compositions of this invention.

The solid matrix, amounting to 40 to 70 parts by weight, for every 100 parts by weight of 35 the aqueous component (a) plus said matrix, consists essentially of 18 to 30 parts by weight of the volatile fluid (b), 1 to 5 parts by weight of the polydiorganosiloxanepolyoxyalkylene copolymer (d) and 21 to 35 parts by weight of the mixture of stick- forming components (c) plus (e). In the preferred embodiment above the solid matrix amounts to 50 to 60 parts by weight.

The mixture of sti6k-forming components consists essentially of from 1 to 5, preferably 2 to 40 4, parts by weight of the solid alkanoic acid (c) and from 20 to 30 parts by weight of component (e), i.e. the waxy ester or mixture thereof with a solid alkanol, and accounts for from 21 to 35 parts by weight for every 100 parts by weight of components (a) to (e).

According to a particular embodiment of the invention, component (c) of the composition is stearic acid and comprises 2 to 4 percent by weight of the sum total weight of components (a) 45 to (e) and component (e) comprises 20 to 25 percent by weight of the sum total weight of components (a) to (e) and consists of 75 to 100 percent by weight of spermaceti wax and up to percent by weight stearyl alcohol based on the weight of (e).

The hardness of an anti-perspirant stick composition of this invention is increased with increasing amounts of component (e) and by increasing the weight ratio of the solid alkanol to 50 waxy ester in component (e) within the limits delineated above. Hardness is decreased with increasing amounts of the solid alkanoic acid.

The separation-stability of the molten water-in-oil type emulsion from which the anti-perspirant stick composition is cast is directly related to the amount of waxy ester that is present in the compositions of this invention.

The compositions of this invention may further comprise small amounts of inessential components which are used in the cosmetic art. Examples of such components include colourants; perfumes; further hardness-controlling components, such as mineral oil and hydro carbon waxes; non-volatile organopolysiloxanes, such as polydimethylsiloxane fluids having a viscosity of from 10 to 10,000 millipascal-seconds at 25'C, and surfactants, such as those used 60 in the compositions of U.S. Patent No. 4,122,029 and of the above- mentioned U.S. Patent Application No. 46590.

The method of preparation of the anti-perspirant stick compositions of this invention is not critical and may be accomplished in any suitable fashion. The best preparative method currently known is to form a warm solution (60-75'C) of the required amounts of components (b) 65 6 GB2050163A 6 through (e) and thereafter emulsify a required amount of warm component (a) therein using standard emulsifying procedures. Inessential components may be admixed at the desired time. The resulting emulsion has long term stability at temperatures commonly used during preparing, holding and pouring the emulsion. On cooling, the emulsion solidifies to a uniform, non-leaking anti-perspirant stick of the dry-feeling type.

The following specific components and Examples are disclosed for the purpose of further illustrating the invention. All percentages and parts are by weight, and all pressures were measured in millimetres of mercury and were converted to kilopascals by multiplying by 0. 1333224 and rounding off.

Polydiorganosiloxane-polyoxyalkylene Copolymer-The polydiorganosiloxanepolyoxyalkylene copolymer that was used in the following examples, and designated as - Copolymer- in the Table was prepared from tri methylsiloxane-end blocked polydimethylsiloxane having a molecular weight of approximately 30,000 and having an average of approximately 4 of its dimethylsilox ane units replaced with methyl hyd rogensi loxa ne units, and a random equimolar polyglycol copolymer of ethylene oxide and propylene oxide having an average molecular weight of 15 approximately 2550 and having allyloxy endgroups on one end and acetoxy endgroups on the other end. Two hundred and twenty grams of the siloxane, 80.76 grams of the polyglycol and 75.19 grams of isopropanol were mixed and heated to reflux under dry nitrogen in a flask and the resulting solution was catalyzed with 0. 15 mi. of a 1 molar solution of H2PtCl., in isopropanol. The reaction mixture was heated at reflux for one hour and thendevolatilized at 20 1 WC. and 1.33 kilopascals pressure. The polydimethyisiloxane- polyoxyalkylene copolymer product had a siloxane/oxyalkylene weight ratio of approximately 2.7 and - CH2CH2CH20 divalent radicals bonding the polyoxyalkylene portion to the polydimethylsiloxane portion by way of a silicon-carbon bond.

Volatile Liquid-The volatile liquid that was used in the following examples and designated as -Volatile Liquid- in the Table was a commercially available mixture of a major amount of octamethylcyclotetrasiloxane and minor amounts of larger cyclic dimethylsiloxanes.

50% ACH-The anti-perspirant astringent ingredient that was used in the following exam ples, and designated---50% ACH- in the Table was a 50 percent by weight solution of aluminium chlorhydraite in water.

Spermaceti Wax-Two types of synthetic spermaceti wax were used in the compositions.

Spermaceti wax (A) was a synthetic spermaceti wax having a melting range of 51 'C to 55T, an iodine value not exceeding 1.0 and a saponification value of from 109 to 117 and containing the same components as natural spermaceti wax. Spermaceti wax (B) was a synthetic spermaceti wax which meets National Formulary (N.F.) specifications and had a melting range of 43'C to

47'C, an iodine value not exceeding 1.0 and a saponfication value of from 109 to 117.

Compositions-The compositions noted in the following Table were prepared by dissolving one part of the polydiorganosiloxane-polyoxyalkylene copolymer in 9 parts of the volatile liquid mixture of cyclic polydimethylsiloxanes to form a stock solution and blending with a suitable portion thereof, at (30-75'C, the indicated amounts of stearic acid, spermaceti wax, and solid 40 alkanol and sufficient additional volatile liquid to obtain the total amounts of components indicated in the Table. The indicated amount of warm 50% ACH was then slowly added to the warm blend of (b) through (e) while the latter was being agitated in a commercial homogenizer. The resulting emulsion was rated from Excellent to Unstable based on a visual examination of its degree of---colour-,i.e. opalescence. Unstable emulsions have no -colour-.

The molten compositions were poured into a stick mold and were allowed to cool to room temperature. Sticks which crystallized on cooling also oozed fluid, i.e. leaked. Sticks which formed a non-crystalline solid matrix were dry, i.e. did not leak. Dry sticks were further ranked, qualitatively, with respect to harness, by rubbing them on the palmar side of the wrist and noting the glide and payout that occurred.

7 7 GB2050163A 7 Table Components-Parts Composition Volatile Stearic Number (1) 50% ACH Liquid Acid Copolymer 5 1 50 26.00 2.5 1.50 2 50 23.75 2.5 1.25 3 50 23.75 2.5 1.25 4 50 23.75 2.5 1.25 10 50 23.75 2.5 1.25 6 50 23.75 2.5 1.25 7 50 23.75 2.5 1.25 8 50 21.25 2.5 1.25 9a- 50 23.75 0 1.25 15 9b 50 23.75 2.5 1.25 9C(4) 50 26.00 0 1.50 Table Contd Components-Parts Composition Spermaceti Stearyl Properties NumberM WaX(2) Alcohol Emulsion Stick 25 1 20.00(A) 0 Excellent Dry 2 22.50(A) 0 Excellent Dry, -Hardest 3 1 1.25(A) 11.25 Good Dry, Firm 4 5.70(A) 16.80 Acceptable Dry, Harder 5 22.50(13) 0 Excellent Dry, Softest 30 6 11. 2 5(13) 11.25 Good Dry, Softer 7 5.70(13) 16.80 Acceptable Dry, Firm 8 25.00(13) 0 Excellent Dry ga 25.00(A) 0 Excellent Leaked gb 0 2253) Unstable Dry 35 9C(4) 21.50(A) 0 Acceptable Leaked (1) Compositions 9a, gb, 9c are for comparison purposes only.

(2) (A) Synthetic ermaceti wax, m.p. 51-55'C; 40 (B) Synthetic spermaceti wax N.F., m.p, 4347'C.

(3) Cetyl alcohol (4) Also contains 1.5 parts of water-in-oil surfactant having an HLB value of 8.6.

Claims (7)

1. An anti-perspirant composition comprising (a) 30 to 60 parts by weight of an aqueous solution of an astringent agent as a discontinuous phase, dispersed in a solid matrix comprising (b) 18 to 30 parts by weight of a volatile liquid having a normal boiling point of less than 50 25WC. comprising a methylsiloxane fluid having the average unit formula:(CH3)aS'04-a/2 wherein a has an average value of from 2 to 3 inclusive and/or a paraffinic hydrocarbon fluid, 55 (c) 1 to 5 parts by weight of at least one solid alkanoic acid having at least 12 carbon atoms per molecule, (d) 1 to 5 parts by weight of a polydiorgansiloxane-polyoxyalkylene copolymer containing at least one polydiorganosiloxane segment comprising siloxane units of the general unit formula:- --- 60 BbS'04-b/2 wherein b has a value of from 0 to 3, inclusive, there being an average value of approximately 2 R radicals per silcon atom for all siloxane units in the copolymer, and R denotes a ethyl, vinyl or phenyl radical or a divalent radical bonding a polyoxyalkylene segment to the polydiorganosi- 65 8 GB2050163A 8 loxane being methyl; and at least one polVoxyalkylene segment having an average molecular weight of at least 1000 and consisting of from 0 to 50 mol percent polyoxypropylene units and from 50 to 100 mol percent polyoxyethylene units, at least one terminal portion of the polyoxyalkylene segment being bonded to the polydiorganosiloxane segment, any terminal portion of the polyoxyalkylene segment not bonded to the polydiorganosiloxane segment being satisfied by terminating radical, the weight ratio of polydiorganosiloxane segments to polyoxyalkylene segments in the copolymer having a value of from 2 to 8 and (e) 20 to 30 parts by weight of a component comprising at least one waxy ester or a mixture of one part by weight of at least one waxy ester with up to 3 parts by weight of at least one solid alkanol having at least 12 carbon atoms per molecule, the sum total of components (a), 10 (b), (c), (d) and (e) being 100 parts by weight.

2. An anti-perspirant composition according to Claim 1 wherein component (c) is stearic acid and comprises 2 to 4 percent by weight of the sum total weight of components (a) to (e) and component (e) comprises 20 to 25 percent by weight of the sum total weight of components (a) to (e) and consists of 75 to 100 percent by weight of spermaceti wax and up to 25 percent by 1 weight stearyl alcohol based on the weight of (e).

3. An anti-perspirant composition according to Claims 1 or 2, wherein the volatile liquid is a mixture of cyclic dimethylsiloxanes comprising a major proportion of octamethylcyclotetrasilox ane.

4. An anti-perspirant composition according to any of Claims 1 to 3, wherein the aqueous 20 solution of the astringent agent consists of equal weights of water and aluminium chlorhydrate and comprises from 40 to 50 percent by weight of the sum total weight of components (a) to (e).

5. An anti-perspirant composition according to any of Claims 1 to 4, wherein component (d) comprises one polydiorganosiloxane segment having bonded thereto one or more polyoxyalky- 25 lene segments.

6. An anti-perspirant composition according to any of Claims 1 to 5 in stick-form.

7. An anti-perspirant composition according to Claim 1 substantially as herein described with reference to any of the specific Examples.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd.-1 980. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1AY. from which copies may be obtained.